I am working on a project where I have to clear all the data from a JSON array. There seems to be no method like jsonArray.clear(). Also tried jsonArray = new JSONArray(). That too didn't worked. Suggestions please
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5why doesn't jsonArray = new JSONArray() work?thang– thang2013-02-19 01:47:45 +00:00Commented Feb 19, 2013 at 1:47
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6 Answers
Just create a new JSONArray.
JSONArray otherJsonArray = new JSONArray();
Or iterate through the array and remove(int index) the indexes.
http://www.json.org/javadoc/org/json/JSONArray.html#remove(int)
5 Comments
Joseph
But there is no method remove(int) for JSONArray. My IDE is not showing that. I am using Android development tool(Eclipse)
Anew
No method
remove on JSONArray? It's not static, so that's not surprising. It's an instance method, it would be jsonArray.remove(); unless you're not using the same org.json.JSONArray object?Joseph
Am using org.json.JSONArray object. I changed that object to static and still it don't have the method remove()
Anew
You've misunderstood me, the method should exist on the instance (jsonArray), not on the JSONArray class as a static method.
Gastón Saillén
if you iterate incrementally to remove(index) , first time will be 0 and will delete lets say from A,B,C "A" after the second loop with 1 it will delete "C" and for the 3rd loop it will not delete nothing since there is no more things after C , so it will return B and will not delete all the array, you need to iterate decrementally to do it
Just put jsonArray = new JSONArray()
Comments
Creating a new one will work, unless you have passed it as a parameter to a method in which case you need to modify the referenced object as a new reference will not be seen by the calling method.
So if that is the case, do it backwards, that way you won't get your iterator exceeding bounds:
int startingLength = someJsonArray.length();
for (int i = startingLength - 1; i >= 0; i--) {
someJsonArray.remove(i);
}
Comments
And you use that otherJsonArray is already existing then you use
JSONArray otherJsonArray = new JSONArray("[]");
Comments
We can use someJsonArray.pop(index) to remove require record. We can use this code in loop to remove all records.
Comments
I have a situation where I want to remove all the entries from a JSONArray with key "Constants", which is an element in a JSONObject, creating a new JSONArray an assigning it does NOT clear the JSONArray, I have to iterate through the JSONArray and jsonArray.remove(i) on each of them, but there is a second method that works which involves removing the array element, in this case "Constants" completely from the JSONObject and re-adding it as a new JSONArray.
Hereis code with assignment of new array, which does not work, the JSONArray remained unchanged: (I tried both above suggestions for new JSONArray(); and new JSONArray("[]");
JSONObject jsonObj = new JSONObject(metadataOriginalJSON);
if (jsonObj.isJSONArray("Constants")) {
JSONArray constantsArray = jsonObj.getJSONArray("Constants");
constantsArray = new JSONArray();
metadataConstantsRemoved = jsonObj.toString();
}
Here is code for the iteration through the JSONArray which worked:
JSONObject jsonObj = new JSONObject(metadataOriginalJSON);
if (jsonObj.isJSONArray("Constants")) {
JSONArray constantsArray = jsonObj.getJSONArray("Constants");
int i = 0;
int arrayLenSanityCheckPreventEndlessLoop = constantsArray.length();
while (constantsArray.length() > 0 && i < arrayLenSanityCheckPreventEndlessLoop) {
constantsArray.remove(0);
i++;
}
metadataConstantsRemoved = jsonObj.toString();
}The 2nd method that works by removing the entire JSONArray element and re-adding it to the JSONObject:
JSONObject jsonObj = new JSONObject(metadataOriginalJSON);
if (jsonObj.isJSONArray("Constants")) {
jsonObj.remove("Constants");
jsonObj.put("Constants", new JSONArray());
metadataConstantsRemoved = jsonObj.toString();
}